Instructions

I will have to shrink and rearrange some models for my Mosaic M1 and produce netfabb cleaned STL as I go.
The edited files will be renamed with a _100mm suffix to denote fitting on a 100mmx100mm build platform.

The control panel covers the edges of its hole and so doesn't need to be perfect.

The slots for the X and Z should still work fine if they aren't perfectly straight and square as long as the hole is wide enough for the arm to pass through and stops short of the rod mountings at either end. It wouldn't be hard to add some edge covers for these as well to hide any imperfections.

There also looks to be space to use nuts instead of threaded holes but tapping holes isn't hard and can be done using cheap hand tools.

The welding could be replaced by cutting a couple of brackets to bolt the corners.